[@Blazion] Not trying to double post, but realized we haven't addressed your questions. And while I know your second question is one [@LG] can answer, for the first one, I think there's a lot of leeway in terms of digivolution lines. I can speak confidently that as long as it makes sense in some natural progression, it won't be a big deal. 

Digivolutions are such an abstract concept sometimes. Like you'll have a champ form not look like anything resembling the rookie (Patamon to Angemon anyone?). So if you have another dinomon in mind other than Greymon, I'm sure that'll be okay. Hell, my own line that I'm doing for Veemon won't be following the canon-specific line as seen in Digimon Adventure 02 [s]mainly because we never got an official straight shot exveemon line without DNA Digivolution >.>[/s]

But I digress! Make it make sense and I'm sure all is dandy!